Bioclimatic drought trend study through the application of the ombroxeric index. A case study: the province of León (Spain)

The ombroxeric index (OXI), a drought-indicative bioclimatic index based on the Rivas-Martínez Worldwide Bioclimatic Classification System (WBCS), was used in this work to establish the ombroxericity trends in a defined study area: the province of Leon (Spain). On the basis of large time-scale climatological gridded databases (MOPREDAS and MOTEDAS), with data from 1951 to 2010 at monthly, seasonal an annual study level, a Mann-Kendall test-based trend analysis was carried out and a geostatistical interpolation procedure, Empirical Bayesian Kriging (EBK), was applied. Statistically significant increases were revealed in the months of March and June, as well as in the summer period. These increments are greater in the southernmost areas and could be related with changes in some teleconnection patterns. With this up-to-date approach, besides being aware of the direct bioclimate-altering consequences of the climate change, the prediction of the implications in the vegetation is made possible, due to the typological-predictive character of the model of climate-vegetation reciprocity provided by the WBCS.